Memorized Heartbeats
by Chargedlion
Summary: In connection with 4x21. Kara is out for a fly one night when she picks up on Alex's heartbeat. She know's what her heartbeat sounds like normally, and that was not her normal rate. Nightmares. Danvers Sisters. One-Shot.


**Hey guys! So, just a heads up, these characters may be a little OOC. I will try my best and I have done a lot of research about Supergirl lore and I love the Danvers sisters, but I haven't had the opportunity to watch a full episode yet. I, however, did see the crossover episode of the Flash and have watched plenty of clips on YouTube. So bear with me, and I hope you enjoy.**

**-Chargedlion**

xxx

Kara knew Alex's heartbeat. She knew what it sounded like when she was out in the field fighting aliens by her side. She knew what it sounded like when she'd lay her head on her chest during one of their movie nights. She'd known what her heartbeat sounded like since the day they met, but this; this wasn't Alex's regular heartbeat. Something was wrong.

xxx

Kara would sometimes fly around National City at night in order to clear her head. So much goes on all the time that she never gets to think anymore. Besides, if she was already out at night, she could hear if anyone was in trouble and could arrive quickly. But tonight she heard a different cry for help. A mostly silent one to anyone without enhanced hearing. As she passed by Alex's apartment, she picked up on her sister's heartbeat. It was beating unhealthily fast. Kara was reminded of the nightmares she'd have about Krypton's destruction and wondered if Alex was having a bad nightmare of her own. Without even giving it a second thought, she flew over to the window, opened it, and climbed inside.

Sure enough, Alex was whimpering and thrashing around in her sleep. "Ka-ra... don't... go... Kara! No!" Alex muttered, her head jerking to the side.

Kara didn't want to scare her by waking her up abruptly, but she needed to get her out of that nightmare fast. "Alex. Hey, Alex, it's okay, I'm here," Kara whispered, gently touching her shoulder.

Alex's head jerked again and she started panting, desperate to catch her breath. "Kara! I can't... please..."

"Alex!" Kara tried again, louder this time. "I'm right here. Don't be afraid, you didn't lose me."

Alex gasped suddenly and sat up. "No!"

"I'm here," Kara repeating again, which made Alex turn to look at her.

"You... Oh, Kara...," Alex breathed out, tears burning behind her eyelids. "You're okay..."

Kara reached out for her and Alex quickly closed the gap.

"I-I... I'm sorry..."

Kara squeezed Alex's middle, making sure to be mindful of her super strength. "Why are you sorry? You didn't do anyth-"

"I couldn't get to you in time... I couldn't save you..."

"Alex..." Kara trailed off when she remembered what Alex was referring to. Not long ago, she almost died in a battle with Red Daughter. That battle was what triggered Alex into remembering that she was Supergirl. That battle was also when Alex truly realized that she didn't want to live in a world without Kara Danvers. Kara slowly untangled herself from her sister's grasp and backed off. "Hold on." Kara used her super speed to change into the pajamas she had left there for their impromptu sleepovers.

Alex lifted her head up to look at her little sister, the one she had thought she lost. "Kar... I don't know what I would do without you..."

Kara sat next to Alex and offered her something that she used to let her do when Kara was younger. "Here. Put your head on my chest. Feel my heartbeat; I'm really here."

Alex was hesitant. The last time she put her head on Kara's chest she was slowly fading away.

"Come on," Kara softly encouraged. "It'll be okay, I promise."

Alex nodded a little as did as she was told. When she settled her head on her younger sister's chest and focused on her heartbeat, the first thing she noticed was how strong it was; much stronger than the last time she felt it. The second thing she noticed was that Kara had woken her up from the nightmare, despite not being at her apartment prior. And she was in her Supergirl suit before... But she temporarily forgot about that when Kara started to run her fingers through her hair. All she could do at that moment was close her eyes and think about every good memory she shared with Kara. She was okay; her little sister was alive.

Kara leaned down and kissed the top of Alex's head. "I'm never leaving you..."

Alex breathed out as the feeling of tranquility washed over her.

Kara heard Alex's heartbeat slow down. Finally. "Good. It's okay, Alex."

Alex took a deep breath and let it out slowly. "I'm so glad you're okay... It felt so real..." She eventually lifted her head off of Kara's chest so she could look her in the eyes. "A world without you in it is... a world I never want to see..."

Kara gently cupped Alex's face in her hands. "It's not like you to be so pessimistic... Does this go deeper than you're letting on?"

Alex closed the gap between them by touching her forehead to her sister's. "You were dying, Kara..."

Kara's hand slipped down Alex's arm as she searched for Alex's fingers. When she found them, she brushed her thumbs over her knuckles then squeezed her hand. "That wasn't the first time... Why was this one so different?"

Alex gently flipped Kara's hand over and started to lightly tap the palm of Kara's hand. "I felt you slipping away. I got desperate and was in denial for a while... You wouldn't respond to me, you wouldn't take in the sunlight from the grass I pushed into your hand..." She interlaced their fingers before she continued. "That felt more real than all the other times I thought I was going to lose you... Kara, I can't-" She got cut off my Kara pressing her lips to her forehead. Instead of continuing her sentence, she released a soft sigh and remained there until Kara pulled back.

"Alex. I'm here, alive, with you. Can you register that?"

Alex nodded once.

"Okay." Kara adjusted and laid down on her back. "Come on, you too."

Alex followed her lead and laid beside her sister, still looking at her as if she were to look away she would disappear.

Kara snuggled into her side and put her head on her chest. "I'm not going to go anywhere, don't worry."

Alex tilted her head down and buried her nose into Kara's hair. "How did you know?"

Kara lifted her head up. "What?"

Alex's expression softened. "How did you know I was having a nightmare? You weren't at my apartment before."

"I..." Kara sighed. "So much has been going on lately. I mean, with Red Daughter, and you temporarily forgetting I was Supergirl... It's been hard, so tonight I went for a fly around to clear my head. When I went by your apartment, I picked up on your heartbeat. I _know_ your heartbeat, so when I heard how fast it was I knew something was wrong. I just wanted to make sure you were okay."

Alex smiled a little, but it soon faded. "I'm sorry... I was such a jerk towards Supergirl, I didn't know..."

"It's alright, Lex. You know now, and that's what matters." Kara then put her head back on Alex's chest. "Go back to sleep, Alex. Everything is okay."

"Kara?"

"Hmm?"

"I love you."

Kara grinned and snuggled closer. I love you too."


End file.
